Synthesis of Mimicking Plant Cell Wall-Like Anti-Swelling Hydrogels Based on a “Bottom-Up” Strategy and Their Application in Osmotic Energy Harvesting

Abstract

Osmotic energy harvesting via reverse electrodialysis (RED) presents a promising approach for converting salinity gradient energy into usable power. However, the broad implementation of this technology faces significant barriers, including the inherent instability of conventional ion-selective membranes, the intricacy of fabrication techniques, and unresolved environmental challenges. This hydrogel combines the structural and adhesive properties of carboxymethyl cellulose (CMC) and double-bond lignosulfonate sodium (DLS) to enhance antiswelling performance. DLS is functionalized through a hydroxyl-alkyne click reaction, transforming it into a highly reactive supramolecule. Simultaneously, CMC is integrated into the gel network using a choline chloride/acrylic acid deep eutectic solvent, where acrylic acid acts as both a hydrogen bond donor and a polymerizable monomer. The resulting hydrogel demonstrates remarkable ion selectivity and efficient osmotic energy harvesting, achieving an ultralow swelling rate of 0.385, an output power density of 10.10 W m⁻² (double the commercial benchmark of 5.0 W m⁻²), and an ion selectivity of 99.10%. This study underscores the potential of biomass-based hydrogels as sustainable, high-performance materials for osmotic energy harvesting, offering a viable pathway for next-generation energy technologies.